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Ongoing research into the performance of Venturi tubes has found that the current standards for the measurement of wet-gas flows using such devices may need to be reviewed and updated.
“We have highlighted that significant errors can occur with this type of meter due to installation effects,” says the leader of the research team, Flow Measurement Engineer, Emmelyn Graham. “Our initial findings indicate that two key standards need to be reviewed. The next steps in our research will help inform this process.”
The project began in March utilising NEL’s wet gas flow facility. The installation effects being investigated include the orientation of meters and immediate up-stream conditions in the flow that is being measured.
“We’ve found errors that are in the region of 10%,” says Emmelyn. “We are now modifying our test meters to enable further testing. We are also assessing the use of additional measurements to more accurately determine the amount of liquid in gas flows.”
“Current standards for the measurement of wet-gas flows using Venturi tubes cover horizontal installations and two-phase flow,” Emmelyn adds. “However, three-phase conditions exist in the field, as do non-standard installation conditions. It is clear that these issues must be addressed in any review.”
The standards that the NEL team have highlighted for reviewed are ISO/TR 12748:2015 and ISO/TR 11583:2012. ISO/TR 12748:2015 describes production flow measurement of wet natural gas streams. ISO/TR 11583:2012 describes the measurement of wet gas with differential pressure meters, including Venturi tubes.
